title: Entada africana fraction CH₂Cl₂/MEOH 5% inhibits inducible nitric oxide synthase and pro-inflammatory cytokines gene expression induced by lipopolysaccharide in microglia.
abstract: BACKGROUND
  Inflammatory response in the CNS mediated by microglia cells play an important role in host defense and is implicated in the pathology of neurodegenerative diseases. We investigated the capacity of Entada africana to protect microglia from inflammatory insults by exploring the effect of the CH₂Cl₂/MEOH 5% fraction (Ea5) on pro-inflammatory cytokines mRNA expression. Finally, we studied the effect of Ea5 on the inhibition of p38 MAPK Kinase. The results were compared to those obtained with Baicalin, a well reported anti-inflammatory flavonoid.
  
  
  METHODS
  Barks from E. africana were harvested in 2010, in the west region of Cameroon. A crude extract was prepared using CH₂Cl₂/MEOH 1:1 V/V. The crude extract obtained was further fractionated by flash chromatography. A mouse microglia cell line (N9) was stimulated by LPS with or without different concentrations of Baicalin and Ea5. The release of NO was evaluated using the Griess method. The expression of pro-inflammatory cytokines mRNA (TNFα, IL-1β, IL-6) and iNOS/NO were measured by RT- PCR. The inhibition of p38 MAPK Kinase was assessed using ELISA.
  
  
  RESULTS
  We found that Ea5, as well as Baicalin inhibited LPS-induced NO production in a dose dependent manner. Ea5 was most active in term of NO inhibition (87.07%), in comparison to Baicalin (70.85%). The expression of TNFα, IL-1β, IL-6 and iNOS was strongly suppressed by Ea5 in microglia. Ea5 also inhibited the activity of p38MAPK Kinase, up to 30% for the concentrations tested, whereas a prominent inhibition was obtained with Baicalin.
  
  
  CONCLUSIONS
  These results suggest that E. africana may contain promising compounds useful for the treatment of diseases cause by over-activation of microglia such as Alzheimer disease and other neurological diseases.
authors.affiliation: Laboratory of Pharmacology and Toxicology, Department of Biochemistry, University of Yaoundé 1, Yaoundé 1, Cameroon. pmoundipa@hotmail.com.
authors.forename: Brice Ayissi
authors.initials: BA
authors.lastname: Owona
authors.forename: Nico Frederic
authors.initials: NF
authors.lastname: Njayou
authors.forename: Stefan A
authors.initials: SA
authors.lastname: Laufer
authors.forename: Hermann J
authors.initials: HJ
authors.lastname: Schluesener
authors.forename: Paul Fewou
authors.initials: PF
authors.lastname: Moundipa
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D016207:Cytokines / Q000235:genetics / Q000378:metabolism*; D007887:Fabaceae / Q000737:chemistry*; D015870:Gene Expression / Q000187:drug effects*; D008070:Lipopolysaccharides / Q000633:toxicity; D000432:Methanol; D008752:Methylene Chloride; D051379:Mice; D017628:Microglia / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000235:genetics / Q000378:metabolism*; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D016207:Cytokines; D008070:Lipopolysaccharides; D010936:Plant Extracts; D012333:RNA, Messenger; D008752:Methylene Chloride; D052247:Nitric Oxide Synthase Type II; D048051:p38 Mitogen-Activated Protein Kinases; D000432:Methanol